A plasma display panel (hereinafter, referred to as a PDP) is provided with two sheets of glass substrates equipped with electrodes and phosphor layers in a plurality of cells which are separated by walls formed between the substrates. When a cell is discharged by applying voltage between electrodes, UV (ultraviolet) rays are generated, which are attributed to a discharge gas sealed in a cell, and the UV rays activate phosphor resulting in emission of visible light. At present, phosphors predominantly utilized for a PDP application include, for example, (Y, Gd) BO3:Eu (red), Zn2SiO4:Mn (green), BaMgAl10O17:Eu (blue) (for example, refer to patent Document 1).
In recent years, required for a PDP display are, for example, a further improvement in luminance and a more smooth moving image of a display. One of the methods to enhance luminance is an improvement of emission intensity of a phosphor. Specifically, since a green phosphor has a high visual sensitivity, it is important to enhance emission intensity of a green phosphor to improve white luminance. On the other hand, successive display of information within a very short time unit is required for providing smooth moving image of a display, however, Zn2SiO4:Mn (green) has a rather long afterglow, resulting in a problem of causing an after-image and a flicker of an image when the display moves to a next image. Therefore, reduction of afterglow in addition to an improvement of emission intensity is required.
Generally, with respect to zinc silicate phosphors activated with manganese, for example, Zn2SiO:Mn, attempts to control emission time and afterglow time by varying quantity of manganese as an activator have been made.
However, emission intensity and afterglow time are in a trade-off relationship in many cases and there has been a problem of lowering emission intensity when afterglow time is shortened by increasing an amount of a manganese activator.
Further, disclosed have been shortening of afterglow time and enhancement of emission intensity by introducing Ba as an activator in a manganese activated zinc silicate phosphor (Zn2SiO4:Mn) (for example, refer to Non-patent Document 1).
However, it is not fully satisfactory with respect to emission intensity and a reduction effect of afterglow time even when quantity of activator is controlled and particle size distribution is improvement in the above technique, and further improvement is still required.
Further, a phosphor layer of each color utilized in a PDP is deteriorated by ultraviolet ray irradiation and ion bombardment at discharging, resulting in reduction of luminance with increasing lighting time of the PDP. Particularly, with respect to ion bombardment, employed in many PDPs are a method in which a phosphor is provided on the other substrate so as to oppose to a pair of display electrodes via a discharge space and are excited to emit light by ultraviolet rays generated by plane discharge between the display electrodes, to avoid ion bombardment at the discharge, however, these are still not fully satisfactory and improvement of a life time characteristic has been an important problem to improve characteristics of a PDP.
(Patent Document 1) Japanese Patent Publication Open to Public Inspection (hereafter referred to as JP-A) No. 2003-183650
(Non-patent Document 1) Journal of the Electrochemical Society, 150(1), H7-H11 (2003)